End face polishing apparatus and method

ABSTRACT

End face polishing apparatus and method that allow the eccentricity of curvature of an end face of a rod-shaped member to be reduced and the cost to be reduced by efficient use of a lapping sheet, so that the polishing efficiency is improved. In an end face polishing apparatus that polishes a rod-shaped member mounted at a polishing fixture by pressing the rod-shaped member against a lapping member mounted at a polishing plate rotatably and rock-ably supported at the main body of the apparatus, the polishing fixture is secured to a first virtual disk having a prescribed diameter and the lapping member is driven to move relative to the polishing fixture so that the first virtual disk moves along the circumference of a second virtual disk as it rotates, and the second virtual disk moves along the circumference of a third virtual disk as it rotates.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to end face polishing apparatus and method polishing an end face of a rod-shaped member such as optical fibers.

[0002] Fibers for optical communication are adhesively secured in the central hole of a ferrule, a main member of a connector, and then the ferrule end face and the end face of fibers are polished together and thus finished into a smooth, mirror surface. If the polished end faces of the ferrule and the fibers are not vertical to the central axis of the ferrule or if there is a flaw on the polished faces, the precision in positioning such ferrules as they are connected facing each other in an optical connector is lowered, and the loss increases. Therefore, the face of the ferrule including the optical fibers must be polished with high precision.

[0003] A conventional apparatus for polishing the end faces of optical fibers is disclosed for example by Japanese Patent Laid-Open No. 26456/1991. The disclosed end face polishing apparatus includes an eccentric adapter that rotates on a circle concentric with a rotating disc, and a planetary gear that transmits the rotation of a revolution motor to the eccentric adapter. These elements are coupled in a polishing plate, so that the polishing plate is allowed to rotate and revolve, while the end faces of a plurality of ferrules held by a polishing fixture are pressed against a lapping member secured to the polishing plate for lapping.

[0004] Here, a trajectory drawn by the movement of a ferrule relative to a polishing fixture when the tip end face of the ferrule is polished using a lapping sheet as a lapping member is shown in FIGS. 10A and 10B.

[0005] As shown in FIG. 10A, the trajectory by the movement of the conventional polishing plate relative to the polishing fixture is drawn as the ferrule is fixed on the circumference of a first virtual disk 110, and the first virtual disk 110 moves as it rotates along the circumference of a second virtual disk 111. The trajectory by this relative movement of the polishing plate to the polishing fixture takes a hypocycloid as shown in FIG. 10B and as the polishing continues the trajectory becomes dense on the central side and sparse on the outer side.

[0006] The polishing in this manner does not pose any problem in the initial state of polishing, but as the polishing continues, the polishing efficiency is lowered in the inner dense region, in other words, the amount of polishing is different between both sides of the ferrule, in other words between the central side and outer side of the lapping sheet. Therefore, the eccentricity of curvature of the ferrule could be large.

[0007] The localized use of the lapping sheet causes the lapping sheet to be much worn, and the lapping sheet must frequently be exchanged, which increases the polishing cost.

[0008] In the conventional polishing apparatus, the trajectory of an end face on the lapping sheet is of a circle moving on a circumference, and therefore in order to increase the polishing speed, the rotation speed in the revolution or rotation must be increased. When the rotation speed is increased, however, the polishing agent could scatter by the centrifugal force, which makes the polishing difficult.

SUMMARY OF THE INVENTION

[0009] The present invention is in view of the above disadvantages, and it is an object of the present invention to provide end face polishing apparatus and method that allow the eccentricity of curvature of an end face of a rod-shaped member to be reduced and the cost to be reduced by efficient use of a lapping sheet, so that the polishing efficiency is improved.

[0010] An end face polishing apparatus according to a first aspect of the present invention directed to a solution to the above disadvantages polishes a rod-shaped member mounted at a polishing fixture by pressing the rod-shaped member against a lapping member mounted at a polishing plate rotatably and rock-ably supported at the main body of the apparatus and includes driving means for driving the polishing plate to move relative to the polishing fixture so that the polishing fixture is secured to a first virtual disk having a prescribed diameter, the first virtual disk moves along the circumference of a second virtual disk as the first virtual disk rotates, and the second virtual disk moves along the circumference of a third virtual disk as the second virtual disk rotates.

[0011] According to a second aspect of the invention, in the end face polishing apparatus according to the first aspect, the driving means drives the polishing plate so that the second virtual disk has a diameter smaller than the radius of the third virtual disk.

[0012] According to a third aspect of the invention, in the end face polishing apparatus according the first or second aspect, the driving means drives the polishing plate so that the first virtual disk has a diameter smaller than the radius of the second virtual disk.

[0013] According to a fourth aspect of the invention, in the end face polishing apparatus according to any one of the first to third aspects, the driving means drives the polishing plate so that the first virtual disk moves on the circumference of the second virtual disk without slipping as the first virtual disk rotates.

[0014] According to a fifth aspect of the invention, in the end face polishing apparatus according to any one of first to fourth aspects, the driving means drives the polishing plate so that the second virtual disk moves on the circumference of the third virtual disk without slipping as the second virtual disk rotates.

[0015] According to a sixth aspect of the invention, in the end face polishing apparatus according to any one of the first to fifth aspects, a trajectory drawn by the movement of the polishing fixture relative to the second virtual disk is in a roulette shape.

[0016] According to a seventh aspect of the invention, in the end face polishing apparatus according the sixth aspect, the position to secure each rod-shaped member to the polishing plate is on the circumference of the first virtual disk, and the roulette shape is a hypocycloid.

[0017] According to an eighth aspect of the invention, in the end face polishing apparatus according the sixth aspect, the position to secure each rod-shaped member to the polishing plate is on a radius of the first virtual disk or an extension of the radius outside the first virtual disk, and the roulette shape is a hypotrochoid.

[0018] According to a ninth aspect of the invention, in the end face polishing apparatus according to any one of the first to eighth aspects, the driving means includes a first revolution shaft connected in a position deviated from the center of the polishing plate, a rotation shaft centered around the first revolution shaft, and a second revolution shaft. The rotation shaft is provided in a position deviated from the center of the second revolution shaft.

[0019] According to a tenth aspect of the invention, in the end face polishing apparatus according to any one of the first to eighth aspects, the driving means includes a rotation shaft connected to the center of the polishing plate, a first revolution shaft, and a second revolution shaft. The rotation shaft is provided in a position deviated from the center of the first revolution shaft, and the first revolution shaft is provided in a position deviated from the center of the second revolution shaft.

[0020] According to an eleventh aspect of the invention, in the end face polishing apparatus according to the ninth or tenth aspect, the driving means includes an internal gear secured to the apparatus main body, a first transmission gear engaged with the internal gear, a rotation shaft having a second transmission gear at an end opposite to an end on the side of the first transmission gear, and an external gear engaged with the second transmission gear.

[0021] According to a twelfth aspect of the invention, in the end face polishing apparatus according to any one of the eighth to tenth aspects, the first revolution shaft is connected with a driving motor through a revolution timing belt.

[0022] According to a thirteenth aspect of the invention, in the end face polishing apparatus according to the twelfth aspect, the rotation shaft is connected with the driving motor through a rotation timing belt.

[0023] According to a fourteenth aspect of the invention, an end face polishing method polishing a rod-shaped member mounted at a polishing fixture by pressing the rod-shaped member against a lapping member mounted at a polishing plate rotatably and swing-ably supported at an apparatus main body includes driving the polishing plate to move relative to the polishing fixture for polishing the rod-shaped member so that the polishing fixture is secured to a first virtual disk having a prescribed diameter, the first disk moves along the circumference of a second virtual disk as the first virtual disk rotates, and the second virtual disk moves along the circumference of a third virtual disk as the second virtual disk rotates.

[0024] According to a fifteenth aspect of the invention, in the end face polishing method according to the fourteenth aspect, the polishing plate is driven so that the second virtual disk has a diameter smaller than the radius of the third virtual disk.

[0025] According to a sixteenth aspect of the invention, in the end face polishing method according to the fourteenth or fifteenth aspect, the polishing plate is driven so that the first virtual disk has a diameter smaller than the radius of the second virtual disk.

[0026] According to a seventeenth aspect of the invention, in the end face polishing method according to any one of the fourteenth or sixteenth aspect, the polishing plate is driven so that the first virtual disk moves on the circumference of the second virtual disk without slipping as the first virtual disk rotates.

[0027] According to an eighteenth aspect of the invention, in the end face polishing method according to any one of the fourteenth to seventeenth aspects, the polishing plate is driven so that the second virtual disk moves on the circumference of the third virtual disk without slipping as the second virtual disk rotates.

[0028] According to a nineteenth aspect of the invention, in the end face polishing method according to any one of the fourteenth to eighteenth aspects, a trajectory drawn by the movement of the polishing plate relative to the second virtual disk is a roulette shape.

[0029] According to a twentieth aspect of the invention, in the end face polishing method according to the nineteenth aspect, the position to secure each rod-shaped member to the polishing plate is on the circumference of the first virtual disk, and the roulette shape is a hypocycloid.

[0030] According to a twenty-first aspect of the invention, in the end face polishing method according to the nineteenth aspect, the position to secure each rod-shaped member to the polishing plate is on an radius of the first virtual disk or an extension of the radius outside the first virtual disk, and the roulette shape is a hypotrochoid.

[0031] According to a twenty-second aspect of the invention, in the end face polishing method according to any one of the fourteenth to twenty-first aspects, the driving is performed using an X-Y table.

[0032] According to a twenty-third aspect of the invention, in the end face polishing method according to any one of the fourteenth to twenty-second aspects, the speed of driving the polishing plate is variable.

[0033] According to the invention, the difference in the density of the trajectory drawn by the rod-shaped member on the lapping sheet can be eliminated between regions of the sheet. The polishing amount of the end face of the rod-shaped member is not deviated, and the eccentricity of curvature can be reduced while the lapping sheet can be less worn and may have a prolonged useful life.

BRIEF DESCRIPTION OF THE DRAWINGS

[0034]FIG. 1 is a sectional view of a main part of an end face polishing apparatus according to a first embodiment of the present invention;

[0035]FIG. 2 is a schematic diagram for use in illustration of features of driving means in the end face polishing apparatus according to the first embodiment;

[0036]FIG. 3A is a perspective view of a polishing fixture according to the first embodiment;

[0037]FIG. 3B is a sectional view of a main part of the end face polishing apparatus according to the first embodiment;

[0038]FIG. 4 is a diagram for use in illustration of a virtual disc to draw a trajectory according to the first embodiment;

[0039]FIGS. 5A and 5B are diagrams showing a trajectory representing the movement of a rod-shaped member relative to a lapping sheet according to the first embodiment;

[0040]FIGS. 6A and 6B are diagrams showing a trajectory representing the movement of a rod-shaped member relative to a lapping sheet according to a second embodiment of the invention;

[0041]FIGS. 7A and 7B are diagrams showing a trajectory representing the movement of a rod-shaped member relative to a lapping sheet according to a third embodiment of the invention;

[0042]FIG. 8 is a schematic sectional view of a shaft arrangement in an end face polishing apparatus according to a fourth embodiment of the invention;

[0043]FIG. 9 is a schematic sectional view of a shaft arrangement in an end face polishing apparatus according to a fifth embodiment of the invention; and

[0044]FIG. 10 is a diagram showing a trajectory representing the movement of a rod-shaped member relative to a lapping sheet according to a conventional technique.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0045] Embodiments of the present invention will now be described in conjunction with the accompanying drawings.

[0046] First Embodiment

[0047]FIG. 1 is a sectional view of a main part of an end face polishing apparatus according to a first embodiment of the present invention.

[0048] As shown in FIG. 1, on a lapping surface plate 10, an elastic member 11 is provided through an apparatus main body 20 and a lapping sheet 12 is provided on the elastic member 11. An end face of a rod-shaped member is pressed against the lapping sheet 12 for lapping.

[0049] The lower side of the lapping surface plate 10 and a flange portion 31 on a first revolution shaft 30 are coupled through a plurality of securing pins 32 in positions a prescribed distance deviated from the center of the lapping surface plate 10. The lapping surface plate 10 is supported by the first revolution shaft 30 and capable of revolving as it is supported. The first revolution shaft 30 is connected in a rotation shaft 40 in a position a prescribed distance deviated from the center of the rotation shaft 40 through a transmission unit 41 and a securing pin 42.

[0050] The lower part of the first revolution shaft 30 is engaged with a first transmission gear 50 that is engaged with a second transmission gear 51. The second transmission gear 51 is connected concentrically with a third transmission gear 52. The third transmission gear 52 is engaged with an internal gear in the apparatus main body 20.

[0051] The lower part of the rotation shaft 40 is engaged with the internal gear of a rotation portion 53 connected through a rotation timing belt 63 provided outside a pulley for rotation 62 that is connected to the driving shaft 61 of a driving motor 60.

[0052] A second revolution shaft 70 is connected through a pulley for revolution 64 connected to the driving shaft 61 of the driving motor 60 and a revolution timing belt 65. The rotation shaft 40 is positioned a prescribed distance deviated from the center in the second revolution shaft 70.

[0053] The first revolution shaft 30, the rotation shaft 40 and the second revolution shaft 70 form driving means that drives the lapping surface plate 10.

[0054] Features of the driving means for the end face polishing apparatus according to the embodiment will now be described. FIG. 2 is a schematic diagram of the rotation shaft of the end face polishing apparatus.

[0055] In FIG. 2, the apparatus as a whole is in the process of a revolution RE1. The rotation shaft 40 is rotated by an external gear EG1 that has its center deviated from the rotation center of the second revolution shaft 70 by R and is engaged with an internal gear IG1. In the rotation shaft 40, a revolution RE2 around the rotation shaft 40 is performed by a gear G2 engaged through a gear G3 with a gear G1 driven by an external gear EG2 that is engaged with an internal gear IG2.

[0056] Meanwhile, as shown in FIGS. 3A and 3B, a polishing fixture 80 having a plurality of rod-shaped members W such as a ferrule is supported by a supporting mechanism 21 at the apparatus main body 20. Note that FIG. 3A is a perspective view of the polishing fixture and FIG. 3B is a sectional view of a part of the end face polishing apparatus.

[0057] As shown in FIGS. 3A and 3B, the polishing fixture 80 includes a polygonal (hexagonal according to the embodiment) polishing fixture main body 90 each side of which has two recesses 91 to which a side of the rod-shaped member W is fitted, and holding members 100 provided movably in the direction of the surface of the polishing fixture main body 90 in positions facing the recesses 91.

[0058] About in the center of the polishing fixture main body 90, a boss 92 is attached. The boss 92 is urged toward the lapping surface plate 10 and has its movement in the rotation direction restricted by the supporting mechanism 21.

[0059] The holding member 100 is secured to a side of the polishing fixture main body 90 by a securing pin 101. More specifically, the securing pin 101 is penetrated through the holding member 100 and has its tip threadably engaged to the side of the polishing fixture main body 90, so that the holding member 100 is held movably in the surface direction of the polishing fixture main body 90. The rod-shaped member W can be held and secured between the holding member 100 and recess 91.

[0060] The polishing fixture 80 as described above is supported by a pressing shaft 22 that is urged by prescribed pressing force downwardly to the supporting portion 21 a secured to the apparatus main body 20. Here, the tip end of the pressing shaft 22 forms a conical portion 22 a, which is engaged with a tapered fitting hole 92 a in the boss 92 formed in the center of the polishing fixture 80. The supporting portion 21 a is provided with a rotation stop pin 23 parallel to the pressing shaft 22, and the insertion of the tip end of the rotation stop pin 23 in an engagement hole 92 b in the boss 92 restricts the rotation of the polishing fixture 80.

[0061] Now, a trajectory drawn by the relative movement of the lapping surface plate to the polishing fixture as it is driven by the driving means for the end face polishing apparatus will be described in detail. Note that FIG. 4 is a diagram for use in illustration of a virtual disk to draw a trajectory, and FIGS. 5A and 5B show trajectories representing the relative movement of the rod-shaped member to the lapping sheet.

[0062] As shown in FIG. 4, the driving means drives the lapping surface plate 10 to move relative to the polishing fixture so that the polishing fixture is secured to the first virtual disk 110 having a prescribed diameter, the first virtual disk 110 moves along the circumference of a second virtual disk 111 as it rotates, while the second virtual disk 111 moves along the circumference of a third virtual disk 112 as it rotates. Thus, the trajectory representing the relative movement of the rod-shaped member W to the lapping sheet is as shown in FIGS. 5A and 5B.

[0063] Here, the rotation of the first virtual disk 110 corresponds to the rotation of the rotation shaft 40, and the movement of the first virtual disk 110 along the circumference of the second virtual disk 111 corresponds to the revolution RE2 of the first revolution shaft 30. The rotation of the second virtual disk 111 corresponds to the revolution RE2 of the revolution shaft 30, and the movement of the second virtual disk 111 along the circumference of the third virtual disk 112 corresponds to the revolution RE1 of the second revolution shaft 70. More specifically, the first, second, and third virtual disks 110, 111, and 112 have their rotation radii and eccentric radii determined by the rotation shaft 40, the eccentricity of the rotation shaft 40 in the first revolution shaft 30 and the eccentricity of the first revolution shaft 30 in the second revolution shaft 70, respectively. Note that the relation among the rotation shaft, the first and second revolution shafts and the first to third virtual disks is established when the rod-shaped members W are fixed on the circumference of the first virtual disk, and the relation could be otherwise when the rod-shaped members W are fixed on a radius of the first virtual disk or an extension of the radius outside the first virtual disk.

[0064] The driving means preferably drives the polishing fixture so that the diameter of the second virtual disk 111 is smaller than the radius of the third virtual disk 112, and the diameter of the first virtual disk 110 is smaller than the radius of the second virtual disk 111. More specifically, the rotation shaft 40, the first and second revolution shafts 30 and 70 have their radii and eccentricity set in this manner. This is because when the diameter of the second virtual disk 111 is larger than the radius of the third virtual disk 112 and the diameter of the first virtual disk 110 is larger than the radius of the second virtual disk 111, the trajectories representing the relative movement of the rod-shaped members W to the lapping sheet overlap each other to form a locally dense region, and the lapping sheet 12 cannot uniformly be used.

[0065] When the driving means drives the lapping surface plate 10 to move so that the first virtual disk 110 moves along the circumference of the second virtual disk 111 as it rotates, and the second virtual disk 111 moves along the circumference of the third virtual disk 112 as it rotates, each shaft may be set to allow the circumferences to be in contact or not in contact. Alternatively, when the circumferences are set to be in contact, the shafts may be driven so that the circumferences slip with each other or do not slip with each other.

[0066] According to the embodiment, the shafts are so set that the driving means may drive the lapping surface plate 10 to prevent the first and second virtual disks 110 and 111 and the second and third virtual disks 111 and 112 from slipping on each other. In this way, the relative movement between the first and second virtual disks 110 and 111 forms a roulette like trajectory. Here, the roulette like shape is a curve traced by a fixed point on a fixed curve when the curve is rolling on another fixed curve without slipping.

[0067] Furthermore, according to the embodiment, the rod-shaped members W are fixed in positions on the circumference of the first virtual disk 110, so that the trajectory drawn by relative movement of the first and second virtual disks 110 and 111 takes a hypocycloid, approximate rhombus shape as shown in FIG. 5A.

[0068] More specifically, according to the embodiment, the trajectory drawn by the movement of the rod-shaped member W relative to the lapping sheet 12 takes a shape as shown in FIG. 5B by moving the hypocycloid trajectory formed by the first and second virtual disks 110 and 111 to rotate along the circumference of the third virtual disk 112 without slipping.

[0069] In this way, the density of the trajectories of the movement of the rod-shaped members W relative to the lapping sheet can be prevented from being locally high, the lapping sheet 12 can uniformly be used and local wear-out can be prevented. Therefore, the polishing cost can be reduced. The uniformly worn lapping sheet 12 can be used to polish the rod-shaped members W, therefore the deviation of the polishing amount of the tips of the rod-shaped members W can be reduced, and high precision polishing can be performed. As a result, when a ferrule is polished as the rod-shaped member W, the difference in the polishing amount between both sides of the ferrule, i.e., between the central side and the outer side of the lapping sheet 12 can be reduced to reduce the eccentricity of curvature of the ferrule.

[0070] Note that in the end face polishing apparatus, the polishing fixture can be driven by the driving means based on an X-Y table, so that the end face polishing apparatus can be designed without a driving mechanism of a conventional, complicated rotating system including planetary gears or the like for rotation and revolution. In addition, the use of an X-Y table with a large moving distance allows the lapping sheet 12 to be much apart from the rod-shaped members W, and the state of the end faces of the rod-shaped members W can be checked. Then, a lapping sheet 12 with a different roughness can be provided in a different region of the X-Y table and a series of polishing steps from rough polishing to finishing can be performed using the same apparatus.

[0071] In addition, a single or multiple lapping sheets 12 are used to vary the driving speed, so that the polishing speed can be lowered in initial rough polishing, and the load upon the driving system can be reduced in the state with large friction resistance. When the finishing polishing is performed and the friction resistance is low, the driving speed can be increased to reduce the entire polishing time. In this way, the driving speed can be varied using the lapping sheet 12, so that the flying of a polishing agent or the like can be reduced, and the polishing efficiency can be improved.

[0072] Second Embodiment

[0073]FIGS. 6A and 6B show trajectories representing the movement of rod-shaped members relative to a lapping sheet according to a second embodiment.

[0074] According to the second embodiment, the position to fix the rod-shaped member is on an extension in the radial direction outside the first virtual disk 110, and the trajectory by the movement of the lapping surface plate 10 relative to the second virtual disk 111 is a hypotrochoid trajectory drawn by the relative movement between the first and second virtual disks 110 and 111 as shown in FIGS. 6A and 6B.

[0075] The same effects as the above first embodiment can be provided for driving means for drawing the trajectory.

[0076] Third Embodiment

[0077]FIGS. 7A and 7B show a trajectory representing the relative movement of rod-shaped members relative to a lapping sheet according to a third embodiment of the invention.

[0078] According to the third embodiment, the revolution radius R of the first revolution shaft 30 in the end face polishing apparatus is smaller than the second embodiment, and in the end face polishing apparatus, the trajectory drawn by the movement of the lapping surface plate 10 relative to the second virtual disk 111 is a fine hypotrochoid as shown in FIGS. 7A and 7B.

[0079] The same effects as the above first embodiment can be provided for driving means for drawing the trajectory.

[0080] Fourth Embodiment

[0081] In the above first to third embodiments, the face end polishing apparatus has the first revolution shaft 30 in the rotation shaft 40, and the second revolution shaft 70 is outside the rotation shaft 40. Meanwhile, according to this embodiment, the positions of shafts in the driving means are different.

[0082]FIG. 8 is a schematic sectional view of the arrangement of the shafts in the end face polishing apparatus according to the fourth embodiment.

[0083] As shown in FIG. 8, in the driving means in the end face polishing apparatus according to the fourth embodiment, the first revolution shaft 30 is positioned a prescribed distance deviated from the center in the second revolution shaft 70, while the rotation shaft 40 is positioned a prescribed distance deviated from the center in the first revolution shaft 30.

[0084] In the end face polishing apparatus having the shaft arrangement, the lapping surface plate 10 can be driven so that the trajectories the same as those of the first to third embodiments can be drawn.

[0085] Fifth Embodiment

[0086]FIG. 9 is a schematic sectional view of the arrangement of shafts in an end face polishing apparatus according to a fifth embodiment of the invention.

[0087] According to the fifth embodiment, the shafts are in a different arrangement from those of the first to fourth embodiments.

[0088] As shown, for the driving shafts according to the fifth embodiment, the first revolution shaft 30 is positioned a prescribed distance deviated from the center in the second revolution shaft 70, and a rotation gear 40A is provided instead of the rotation shaft at the first revolution shaft 30 on the side of the lapping surface plate 10. The rotation gear 40A is engaged with a transmission shaft 43 provided in a position a prescribed distance deviated from the center in the second revolution shaft 70 to rotate and revolve.

[0089] In the end face polishing apparatus having the shaft arrangement, the lapping surface plate 10 can be driven so that the trajectories the same as those of the first to third embodiments can be drawn.

[0090] In this way, the arrangement of shafts in the end face polishing apparatus according to the invention is not specifically limited.

[0091] Other Embodiments

[0092] As in the foregoing, while the basic structure of the end face polishing apparatus and the end face polishing method are not limited to those of the first to fifth embodiments described above.

[0093] In the first to third embodiments, the trajectory drawn by the movement of the lapping surface plate relative to the second virtual disk 111 is a hypocycloid or hypotrochoid, it may be an epicycloid or epitrochoid.

[0094] In the above first to third embodiments, the driving means drives the lapping surface plate 10 so that the first and second virtual disks 110 and 111 and the second and third virtual disks 111 and 112 move without slipping as they rotate and the trajectories formed by the relative movements form a roulette shape. Meanwhile, the lapping surface plate may be driven so that the disks move as they rotate and slip. When the driving means drives the lapping surface plate in this way, the same effects as those of the above described first to fifth embodiments may be provided.

[0095] As in the foregoing, by the end face polishing apparatus and the end face polishing method according to the present invention, the driving means drives the polishing plate to move relative to the polishing fixture so that the polishing fixture is secured to a first virtual disk having a prescribed diameter, the first virtual disk moves along the circumference of a second virtual disk as it rotates, while the second virtual disk moves along the circumference of a third virtual disk as it rotates. Therefore, the useful life of the lapping sheet can be prolonged and the polishing precision for the rod-shaped members can be improved. In addition, the lapping sheet can efficiently be used, so that the polishing time can be shortened. 

What is claimed is:
 1. An end face polishing apparatus for polishing a rod-shaped member comprising: a polishing plate rotatably and rock-ably supported at the main body of the apparatus, a lapping member mounted on the polishing plate, driving means for driving the polishing plate to move relative to the polishing fixture so that the polishing fixture is secured to a first virtual disk having a prescribed diameter, the first virtual disk moves along the circumference of a second virtual disk as the first virtual disk rotates, and the second virtual disk moves along the circumference of a third virtual disk as the second virtual disk rotates.
 2. The end face polishing apparatus according to claim 1, wherein the driving means drives the polishing plate so that the second virtual disk has a diameter smaller than the radius of the third virtual disk.
 3. The end face polishing apparatus according to claim 1, wherein the driving means drives the polishing plate so that the first virtual disk has a diameter smaller than the radius of the second virtual disk.
 4. The end face polishing apparatus according to claim 1, wherein the driving means drives the polishing plate so that the first virtual disk moves on the circumference of the second virtual disk without slipping as the first virtual disk rotates.
 5. The end face polishing apparatus according to claim 1, wherein the driving means drives the polishing plate so that the second virtual disk moves on the circumference of the third virtual disk without slipping as the second virtual disk rotates.
 6. The end face polishing apparatus according to claim 1, wherein a trajectory drawn by the movement of the polishing fixture relative to the second virtual disk is in a roulette shape.
 7. The end face polishing apparatus according to claim 6, wherein the position to secure each the rod-shaped member to the polishing plate is on the circumference of the first virtual disk, and the roulette shape is a hypocycloid.
 8. The end face polishing apparatus according to claim 6, wherein the position to secure each the rod-shaped member to the polishing plate is on a radius of the first virtual disk or an extension of the radius outside the first virtual disk, and the roulette shape is a hypotrochoid.
 9. The end face polishing apparatus according to claim 1, wherein the driving means comprises a first revolution shaft connected in a position deviated from the center of the polishing plate, a rotation shaft centered around the first revolution shaft, and a second revolution shaft, the rotation shaft being provided in a position deviated from the center of the second revolution shaft.
 10. The end face polishing apparatus according to claim 1, wherein the driving means comprises a rotation shaft connected to the center of the polishing plate, a first revolution shaft, and a second revolution shaft, the rotation shaft being provided in a position deviated from the center of the first revolution shaft, the first revolution shaft being provided in a position deviated from the center of the second revolution shaft.
 11. The end face polishing apparatus according to claim 9, wherein the driving means comprises an internal gear secured to the apparatus main body, a first transmission gear engaged with the internal gear, a rotation shaft having a second transmission gear at an end opposite to an end on the side of the first transmission gear, and an external gear engaged with the second transmission gear.
 12. The end face polishing apparatus according to claim 8, wherein the first revolution shaft is connected with a driving motor through a revolution timing belt.
 13. The end face polishing apparatus according to claim 12, wherein the rotation shaft is connected with the driving motor through a rotation timing belt.
 14. An end face polishing method polishing a rod-shaped member mounted at a polishing fixture by pressing the rod-shaped member against a lapping member mounted at a polishing plate rotatably and swing-ably supported at an apparatus main body, comprising driving the polishing plate to move relative to the polishing fixture for polishing the rod-shaped member so that the polishing fixture is secured to a first virtual disk having a prescribed diameter, the first disk moves along the circumference of a second virtual disk as the first virtual disk rotates, and the second virtual disk moves along the circumference of a third virtual disk as the second virtual disk rotates.
 15. The end face polishing method according to claim 14, wherein the polishing plate is driven so that the second virtual disk has a diameter smaller than the radius of the third virtual disk.
 16. The end face polishing method according to claim 14, wherein the polishing plate is driven so that the first virtual disk has a diameter smaller than the radius of the second virtual disk.
 17. The end face polishing method according to claim 14, wherein the polishing plate is driven so that the first virtual disk moves on the circumference of the second virtual disk without slipping as the first virtual disk rotates.
 18. The end face polishing method according to claim 14, wherein the polishing plate is driven so that the second virtual disk moves on the circumference of the third virtual disk without slipping as the second virtual disk rotates.
 19. The end face polishing method according to claim 14, wherein a trajectory drawn by the movement of the polishing plate relative to the second virtual disk is a roulette.
 20. The end face polishing method according to claim 19, wherein the position to secure each the rod-shaped member to the polishing plate is on the circumference of the first virtual disk, and the roulette shape is in a hypocycloid.
 21. The end face polishing method according to claim 19, wherein the position to secure each the rod-shaped member to the polishing plate is on an radius of the first virtual disk or an extension of the radius outside the first virtual disk, and the roulette shape is a hypotrochoid.
 22. The end face polishing method according to claim 14, wherein the driving is performed using an X-Y table.
 23. The end face polishing method according to claim 14, wherein the speed of driving the polishing plate is variable. 